1. Technical Field of the Invention
The present invention relates generally to a refrigeration system which may be employed in air conditioners, refrigerators, and the like, and more particularly to an improved compressor for such a refrigeration system which uses a refrigeration oil insoluble in refrigerant.
2. Background of the Related Art
Japanese Patent First Publication No. 5-157379 discloses a conventional refrigeration system as shown in FIG. 8. This refrigeration system includes a horizontal refrigerant compressor 100, a condenser 108, a capillary tube 109, and an evaporator 110. A refrigerant gas introduced through a suction pipe 102 enters a cylinder 103 of the refrigerant compressor 100 so that it is compressed in a compression chamber 104 and is discharged into an enclosed chamber 105. The refrigerant gas discharged in the chamber 105 usually contains much refrigeration oil 106 which is partly separated in the chamber 105, while the remainder thereof is discharged from a discharge pipe 107 to the condenser 108. The refrigeration oil 106 includes oil insoluble in refrigerant for improvement of the electric insulation and the handling of assembling parts. The refrigerant gas introduced into the condenser 108 is subsequently reduced in pressure by the capillary tube 109 and then evaporated in the evaporator 110 for cooling a refrigerating chamber.
The above prior art refrigeration system, however, has suffered from a drawback in that a great volume of the refrigeration oil is discharged into a cooling system (i.e., condenser, capillary tube, and evaporator) together with the refrigerant gas. Particularly, when using a refrigeration oil insoluble in the refrigerant, it becomes difficult to return to the compressor completely. This results in lack of the refrigeration oil in the refrigerant compressor.
Additionally, reducing the viscosity of the refrigeration oil for increasing a returned amount thereof to the compressor gives rise to the problem of wear-out of sliding parts of the compressor.